Switching system



Nov. 6, 1928.

R. G. BERTHOLD swncnme SYSTEM Filed June 22, 1926 MAMA 1 mm Patented Nov. 6,; 1928.

" UNITED STATES'PATENT OFFICE.

RUDOLF G. BER'IHOLD, OF IBER LIN-SIEMENSSTADT, GERMANY ASSIGNOR TO SIEMENS SCHUGKERTWERKE GESELLSCHAFT MIT BESCHRKNKTER HAFIUNG, OF SIEMENS- STADT, NEAR BERLIN, GERMANY, A CORPORATION OF GERMANY.

SWITCHING SYSTEM.

Application filed June 22, 1926, Serial No. 117,793, and in Germany .Tune 27, 1925.

My invention relates to a switching system in which an oscillatory circuit is connected in parallel relation or shunt to the main switch and takes up the energy of the circuit to be broken.

It is well known that disturbing phenomena in the form of back-firing or sparking develop at the switch knives when making or breaking electric circuits, particularly such of comparatively high capacity. Such disturbing influences are particularly noticeable when alternating current circuits are broken. The chief reason for this is that the energy stored in the circuit to be broken must be destroyed either inductively or capacitatively the moment when the circuit is interrupted so that an arc is formed.

In order to keep this energy away from the contacts of the switch proper, it has already been proposed to connect an oscillatory circuit in parallel relation or shunt to the switch, said oscillatory circuit being tuned to voltage resonance when alternating current circuits are to be interrupted.

The known arrangement have the disadvantage that it is necessary to construct the oscillatory circuit for large capacities to be disconnected for a correspondingly large energy consumption. This involves lar e and expensive condensers. The size of t e oscillatory circuit may according to my invention be considerably reduced by also connecting in parallel relation to the main switch a gas discharge tube which in the case of alternating current has the task to take up the current rush up to the first passage of the alternating current through the zero value. The ignition of the gas discharge tube is preferably effected by means of ignition electrodes which are excited from the oscillatory circuit.

An embodiment of my invention is diagrammatically illustrated in the accompanymg drawing by way of example. Two oscil latory circuits 7 and 8 are here connected in series with each other and in parallel relation or shunt to the main switch 3. A mercury vapor discharge tube 11 with two mercury electrodes 12 and 13 and two ignition electrodes 10 is furthermore also connected in parallel relation to the switch 3. The excitation of the ignition electrodes takes place from the secondary winding of a transformer 9 whose primary winding is connected in series ,zero in the leads and thus also with the two oscillatory circuits 7 and 8. When the main switch 3 is opened the two oscillatory circuits 7 and 8 are first charged. A considerable rush of current therefore flows through the transformer 9 and the arc is struck in the mercury vapor tube by the excitation of the ignition electrodes 10. It is well known that after the charging of the oscillatory circuit the current becomes practically in the transformer 9. Ignition energy is thus no longer supplied to the electrodes 10 so that the mercury vapor tube is also extinguished during the next passage of the current through zero. In order to avoid the high resistance at the switch 3 for the ignition circuit, the middle of the secondary winding of the transformer 9 is connected with the two main electrodes 12 and 13 of the discharge tube through stopping condensers 14:. In this arrangementa switch for the ultimate disconnection of the oscillatory circuit is no longer necessary. It will be understood that the excitation of the elec trodes from the oscillatory circuits may be accomplished in any other suitable manner known in the art. 7

Instead of switching the oscillatory circuit of constant natural frequency into the main circuit and out ofit,its natural frequency may also be made variable and it may at first when opening the main switch be adjusted out of tune in relation to the system frequency. The resistance of the oscillatory circuit is then comparatively low and the current to be switched off flows for the larger part throu h the oscillatory circuit instead of through t e main switch. Now the oscillatory circuit is adjusted to the frequency of the system and thus the current flowing through the oscillatory circuit is gradually weakened. The oscillatory circuit itself may then be ultimately disconnected by opening a switch. The tuning of the oscillatory circuits 7 and 8 may be effected for instance by means of the adjustment of control levers 17 and 18 respectively on taps 15 and 16 which lead to the inductance coils contained in these circuits. Tuning 0);- pedients of this character are well known in the art and may be modified by any skilled designer to suit the particular condition under which they are employed.

Various modifications and changes may be made without departing from the spirit and the scope of the invention, and I desire, therefore, that only such limitations shall 'be placed thereon as are imposed by the prior art.

I claim as my invention l. The combination of an electric circuit, a main switch in said circuit, an oscillatory circuit having an inductance and a capacity connected in parallel to each other, said circuit being connected in parallel relation to said main switch and adapted to take up the energy of said electric circuit to be broken, a gas discharge tube also connected in parallel rela tion to said main switch, ignition electrodes upon said gas discharge tube, and electric connections adapted to excite said ignition electrodes from said oscillatory circuit.

2. The combination of an electric circuit, a main switch in said circuit, an oscillatory circuit connected in parallel relation to said 20 main switch and adapted to take up the energy of said electric circuit to be broken, a gas dischar e tube also connected in parallel relation to said main switch, ignition electrodes upon said gas discharge tube, and a coupling device connected in series with said'oscillatory circuit and adapted to excite the ignition electrodes of said gas discharge tube.

3. The combination of an electric circuit, a main switch in said circuit, an oscillatory circuit connected in parallel relation to'said main switch and adapted to take up the energy ofsaid electric circuit to be broken, a gas discharge tube also connected in parallel relation to said main switch, ignition electrodes upon said gas discharge tube, a transformer whose primary winding is connected in series with the oscillatory circuit, and connections be tween the secondary winding of the transformer and the ignition electrodes ofsaid gas discharge tube.

In testimony whereof I afiix my signature.-

RUDOLF G. BERTHOLD. 

